From 9f09f649ca3350cdb49c81f7d5ac6e64a4d7e1a1 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Fri, 20 Dec 2019 22:10:36 -0500
Subject: [PATCH] teach logfc() to handle prefices, give it saner calling
 conventions

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 fs/fs_context.c            | 63 ++++++++++----------------------------
 include/linux/fs_context.h | 16 ++++++----
 2 files changed, 27 insertions(+), 52 deletions(-)

diff --git a/fs/fs_context.c b/fs/fs_context.c
index ea97a2411e83..fb6329c21384 100644
--- a/fs/fs_context.c
+++ b/fs/fs_context.c
@@ -388,64 +388,33 @@ EXPORT_SYMBOL(vfs_dup_fs_context);
  * @fc: The filesystem context to log to.
  * @fmt: The format of the buffer.
  */
-void logfc(struct fs_context *fc, const char *fmt, ...)
+void logfc(struct fc_log *log, const char *prefix, char level, const char *fmt, ...)
 {
-	static const char store_failure[] = "OOM: Can't store error string";
-	struct fc_log *log = fc ? fc->log : NULL;
-	const char *p;
 	va_list va;
-	char *q;
-	u8 freeable;
+	struct va_format vaf = {.fmt = fmt, .va = &va};
 
 	va_start(va, fmt);
-	if (!strchr(fmt, '%')) {
-		p = fmt;
-		goto unformatted_string;
-	}
-	if (strcmp(fmt, "%s") == 0) {
-		p = va_arg(va, const char *);
-		goto unformatted_string;
-	}
-
-	q = kvasprintf(GFP_KERNEL, fmt, va);
-copied_string:
-	if (!q)
-		goto store_failure;
-	freeable = 1;
-	goto store_string;
-
-unformatted_string:
-	if ((unsigned long)p >= (unsigned long)__start_rodata &&
-	    (unsigned long)p <  (unsigned long)__end_rodata)
-		goto const_string;
-	if (log && within_module_core((unsigned long)p, log->owner))
-		goto const_string;
-	q = kstrdup(p, GFP_KERNEL);
-	goto copied_string;
-
-store_failure:
-	p = store_failure;
-const_string:
-	q = (char *)p;
-	freeable = 0;
-store_string:
 	if (!log) {
-		switch (fmt[0]) {
+		switch (level) {
 		case 'w':
-			printk(KERN_WARNING "%s\n", q + 2);
+			printk(KERN_WARNING "%s%s%pV\n", prefix ? prefix : "",
+						prefix ? ": " : "", &vaf);
 			break;
 		case 'e':
-			printk(KERN_ERR "%s\n", q + 2);
+			printk(KERN_ERR "%s%s%pV\n", prefix ? prefix : "",
+						prefix ? ": " : "", &vaf);
 			break;
 		default:
-			printk(KERN_NOTICE "%s\n", q + 2);
+			printk(KERN_NOTICE "%s%s%pV\n", prefix ? prefix : "",
+						prefix ? ": " : "", &vaf);
 			break;
 		}
-		if (freeable)
-			kfree(q);
 	} else {
 		unsigned int logsize = ARRAY_SIZE(log->buffer);
 		u8 index;
+		char *q = kasprintf(GFP_KERNEL, "%c %s%s%pV\n", level,
+						prefix ? prefix : "",
+						prefix ? ": " : "", &vaf);
 
 		index = log->head & (logsize - 1);
 		BUILD_BUG_ON(sizeof(log->head) != sizeof(u8) ||
@@ -457,9 +426,11 @@ void logfc(struct fs_context *fc, const char *fmt, ...)
 			log->tail++;
 		}
 
-		log->buffer[index] = q;
-		log->need_free &= ~(1 << index);
-		log->need_free |= freeable << index;
+		log->buffer[index] = q ? q : "OOM: Can't store error string";
+		if (q)
+			log->need_free |= 1 << index;
+		else
+			log->need_free &= ~(1 << index);
 		log->head++;
 	}
 	va_end(va);
diff --git a/include/linux/fs_context.h b/include/linux/fs_context.h
index c7c69640a6c6..d18ff422e942 100644
--- a/include/linux/fs_context.h
+++ b/include/linux/fs_context.h
@@ -181,9 +181,13 @@ struct fc_log {
 	char		*buffer[8];
 };
 
-extern __attribute__((format(printf, 2, 3)))
-void logfc(struct fs_context *fc, const char *fmt, ...);
+extern __attribute__((format(printf, 4, 5)))
+void logfc(struct fc_log *log, const char *prefix, char level, const char *fmt, ...);
 
+#define __logfc(fc, l, fmt, ...) ({		\
+	struct fs_context *__fc = (fc);		\
+	logfc(__fc ? __fc->log : NULL, NULL,	\
+		l, fmt, ## __VA_ARGS__);})
 /**
  * infof - Store supplementary informational message
  * @fc: The context in which to log the informational message
@@ -192,7 +196,7 @@ void logfc(struct fs_context *fc, const char *fmt, ...);
  * Store the supplementary informational message for the process if the process
  * has enabled the facility.
  */
-#define infof(fc, fmt, ...) ({ logfc(fc, "i "fmt, ## __VA_ARGS__); })
+#define infof(fc, fmt, ...) __logfc(fc, 'i', fmt, ## __VA_ARGS__)
 
 /**
  * warnf - Store supplementary warning message
@@ -202,7 +206,7 @@ void logfc(struct fs_context *fc, const char *fmt, ...);
  * Store the supplementary warning message for the process if the process has
  * enabled the facility.
  */
-#define warnf(fc, fmt, ...) ({ logfc(fc, "w "fmt, ## __VA_ARGS__); })
+#define warnf(fc, fmt, ...) __logfc(fc, 'w', fmt, ## __VA_ARGS__)
 
 /**
  * errorf - Store supplementary error message
@@ -212,7 +216,7 @@ void logfc(struct fs_context *fc, const char *fmt, ...);
  * Store the supplementary error message for the process if the process has
  * enabled the facility.
  */
-#define errorf(fc, fmt, ...) ({ logfc(fc, "e "fmt, ## __VA_ARGS__); })
+#define errorf(fc, fmt, ...) __logfc(fc, 'e', fmt, ## __VA_ARGS__)
 
 /**
  * invalf - Store supplementary invalid argument error message
@@ -222,6 +226,6 @@ void logfc(struct fs_context *fc, const char *fmt, ...);
  * Store the supplementary error message for the process if the process has
  * enabled the facility and return -EINVAL.
  */
-#define invalf(fc, fmt, ...) ({	errorf(fc, fmt, ## __VA_ARGS__); -EINVAL; })
+#define invalf(fc, fmt, ...) (errorf(fc, fmt, ## __VA_ARGS__), -EINVAL)
 
 #endif /* _LINUX_FS_CONTEXT_H */